Turns out the most COVID-free place on the planet might just be shark-infested waters. In new findings published in Nature Communications, researchers say they have discovered that a protein unique to sharks is able to neutralize the COVID-19 virus and its variants. “These small antibody-like proteins can get into nooks and crannies that human antibodies cannot access,” Aaron LeBeau, a pathologist from the University of Wisconsin-Madison and a co-author of the new study, said in a statement. “They can form these very unique geometries. This allows them to recognize structures in [coronavirus] proteins that our human antibodies cannot.”
The proteins, called VNARs, are produced by shark immune systems naturally. They’re about one-tenth of the size of human antibodies, making them small and nimble enough to edge their way into binding with proteins produced by infectious pathogens and halting their function.
LeBeau and his team tested the antibody function of shark VNARs against infectious and non-infectious versions of SARS-CoV-2 (the virus that causes COVID-19). Out of billions of VNARs, they found three that were especially effective at stopping the virus from infecting human cells.
One version in particular, called 3B4, is able to attach on a viral spike protein that is common across different types of coronaviruses and different SARS-CoV-2 variants, like Delta. This mechanism meant 3B4 was highly successful in neutralizing other coronaviruses in the lab, including WIV1-CoV (which is endemic to bats but can also infect human cells, and is thought to be the origin of SARS-CoV-2), SARS-CoV-1 (responsible for the SARS outbreak in 2003), and the MERS virus.
VNARs haven’t been tested in humans yet, and it’s unlikely that clinical trials will be completed in time to make VNARs available to fight the current COVID pandemic (though at the rate things are going, never say never). More likely, the authors emphasized, VNARs could be turned into a tool to combat future coronavirus outbreaks in humans and stop a new pandemic from forming. It could be quite easy and affordable to make a cocktail of multiple shark VNARS and deploy it as an early treatment, especially if a vaccine isn’t available.
“The big issue is there are a number of coronaviruses that are poised for emergence in humans,” said LeBeau. “What we’re doing is preparing an arsenal of shark VNAR therapeutics that could be used down the road for future SARS outbreaks. It’s a kind of insurance against the future.”